What could cause extremely high effort to release a Tost CG hook on aTwin Astir?

[Bill D]

The scenario is winch rope break practice with the instructor pulling the release to simulate rope breaks.

I'm not talking about just an ordinary hard pull. This is a maximum-effort, adrenaline pumped, two-handed strain to get the release to work.

On the ground, the CG hook checks out as a little stiffer than one might prefer but otherwise normal. But trying for a mid-winch launch release it requires all the strength I can muster using both hands. Tost CG hook pull effort is not supposed to be dependent on rope tension.

The pull cable runs and pulleys have been checked and re-checked. The Tost CG hook itself is new and seems to work as advertised. There is nothing obvious one can see with the seat pans and instrument pedestal cover removed.

Any ideas?

[Bill T]

I believe I remeber a Kestral that had a "stiff release" issue. He removed the seat pan and discovered that the pan was depressing with his weight in it and binding the cable. But you said you have removed the seat pans and checked all of the cables.

My second guess would have been that there was a worn spot or nick in the "jaws" of the TOST release that might be catching on the ring under strain. But you said the TOST was fairly new. Is the TOST ring in fairly good shape and not one of the imposters that were on the market a few years back?

It would be great if you could have a cable under load at GS=0 to visually watch the release mechanism, but that is not a safe venture without a lot of precautions in set up.

BillT

[Bill D]

On Sunday, May 31, 2015 at 6:43:19 PM UTC-6, Bill T wrote:
> I believe I remeber a Kestral that had a "stiff release" issue. He removed the seat pan and discovered that the pan was depressing with his weight in it and binding the cable. But you said you have removed the seat pans and checked all of the cables.
>
> My second guess would have been that there was a worn spot or nick in the "jaws" of the TOST release that might be catching on the ring under strain.. But you said the TOST was fairly new. Is the TOST ring in fairly good shape and not one of the imposters that were on the market a few years back?
>
> It would be great if you could have a cable under load at GS=0 to visually watch the release mechanism, but that is not a safe venture without a lot of precautions in set up.
>
> BillT

Both the CG hook and the ring pair are brand new. My only guess (AKA pure speculation) is an improper (and unrecorded) repair left the whole forward fuselage weak so it is deforming under winch launch loads causing the yellow-ball to CG hook cable system to bind. FWIW, I do not suspect the hook itself.

Bill D

[Bill D]

On Sunday, May 31, 2015 at 6:58:47 PM UTC-6, Bill D wrote:
> On Sunday, May 31, 2015 at 6:43:19 PM UTC-6, Bill T wrote:
> > I believe I remeber a Kestral that had a "stiff release" issue. He removed the seat pan and discovered that the pan was depressing with his weight in it and binding the cable. But you said you have removed the seat pans and checked all of the cables.
> >
> > My second guess would have been that there was a worn spot or nick in the "jaws" of the TOST release that might be catching on the ring under strain. But you said the TOST was fairly new. Is the TOST ring in fairly good shape and not one of the imposters that were on the market a few years back?
> >
> > It would be great if you could have a cable under load at GS=0 to visually watch the release mechanism, but that is not a safe venture without a lot of precautions in set up.
> >
> > BillT
>
> Both the CG hook and the ring pair are brand new. My only guess (AKA pure speculation) is an improper (and unrecorded) repair left the whole forward fuselage weak so it is deforming under winch launch loads causing the yellow-ball to CG hook cable system to bind. FWIW, I do not suspect the hook itself.
>
> Bill D

FWIW, CS-22 regs say a CG hook operating force can't exceed 140N (31.5 Lbs-F) I'm guessing this one takes 200 Lbs-F or more.

[Frank Whiteley]

On Sunday, May 31, 2015 at 7:02:37 PM UTC-6, Bill D wrote:
> On Sunday, May 31, 2015 at 6:58:47 PM UTC-6, Bill D wrote:
> > On Sunday, May 31, 2015 at 6:43:19 PM UTC-6, Bill T wrote:
> > > I believe I remeber a Kestral that had a "stiff release" issue. He removed the seat pan and discovered that the pan was depressing with his weight in it and binding the cable. But you said you have removed the seat pans and checked all of the cables.
> > >
> > > My second guess would have been that there was a worn spot or nick in the "jaws" of the TOST release that might be catching on the ring under strain. But you said the TOST was fairly new. Is the TOST ring in fairly good shape and not one of the imposters that were on the market a few years back?
> > >
> > > It would be great if you could have a cable under load at GS=0 to visually watch the release mechanism, but that is not a safe venture without a lot of precautions in set up.
> > >
> > > BillT
> >
> > Both the CG hook and the ring pair are brand new. My only guess (AKA pure speculation) is an improper (and unrecorded) repair left the whole forward fuselage weak so it is deforming under winch launch loads causing the yellow-ball to CG hook cable system to bind. FWIW, I do not suspect the hook itself.
> >
> > Bill D
>
> FWIW, CS-22 regs say a CG hook operating force can't exceed 140N (31.5 Lbs-F) I'm guessing this one takes 200 Lbs-F or more.

New hook, correct hook? Correctly installed? Cracked plates? Is replacement of plates logged? Sounds like hook could be rotating under tension but you can't duplicate on ground. Cracked or broken mount plates could perhaps cause this. See these SB's
http://www.ltb-lindner.com/g-103-ad-sb.html?file=tl_files/ltb_lindner/pdf/G%20103%20LTA%20%26%20TM%20Englisch/315-62-2%20%20CofG%20hook.pdf
http://www.ltb-lindner.com/g-103-ad-sb.html?file=tl_files/ltb_lindner/pdf/G%20103%20LTA%20%26%20TM%20Englisch/315-62%20%20CofG%20hook.pdf

[Frank Whiteley]

On Sunday, May 31, 2015 at 7:02:37 PM UTC-6, Bill D wrote:
> On Sunday, May 31, 2015 at 6:58:47 PM UTC-6, Bill D wrote:
> > On Sunday, May 31, 2015 at 6:43:19 PM UTC-6, Bill T wrote:
> > > I believe I remeber a Kestral that had a "stiff release" issue. He removed the seat pan and discovered that the pan was depressing with his weight in it and binding the cable. But you said you have removed the seat pans and checked all of the cables.
> > >
> > > My second guess would have been that there was a worn spot or nick in the "jaws" of the TOST release that might be catching on the ring under strain. But you said the TOST was fairly new. Is the TOST ring in fairly good shape and not one of the imposters that were on the market a few years back?
> > >
> > > It would be great if you could have a cable under load at GS=0 to visually watch the release mechanism, but that is not a safe venture without a lot of precautions in set up.
> > >
> > > BillT
> >
> > Both the CG hook and the ring pair are brand new. My only guess (AKA pure speculation) is an improper (and unrecorded) repair left the whole forward fuselage weak so it is deforming under winch launch loads causing the yellow-ball to CG hook cable system to bind. FWIW, I do not suspect the hook itself.
> >
> > Bill D
>
> FWIW, CS-22 regs say a CG hook operating force can't exceed 140N (31.5 Lbs-F) I'm guessing this one takes 200 Lbs-F or more.

Has this changed since winch testing and training started, or remained consistent?

Frank W

[Bill D]

On Sunday, May 31, 2015 at 7:46:35 PM UTC-6, Frank Whiteley wrote:
> On Sunday, May 31, 2015 at 7:02:37 PM UTC-6, Bill D wrote:
> > On Sunday, May 31, 2015 at 6:58:47 PM UTC-6, Bill D wrote:
> > > On Sunday, May 31, 2015 at 6:43:19 PM UTC-6, Bill T wrote:
> > > > I believe I remeber a Kestral that had a "stiff release" issue. He removed the seat pan and discovered that the pan was depressing with his weight in it and binding the cable. But you said you have removed the seat pans and checked all of the cables.
> > > >
> > > > My second guess would have been that there was a worn spot or nick in the "jaws" of the TOST release that might be catching on the ring under strain. But you said the TOST was fairly new. Is the TOST ring in fairly good shape and not one of the imposters that were on the market a few years back?
> > > >
> > > > It would be great if you could have a cable under load at GS=0 to visually watch the release mechanism, but that is not a safe venture without a lot of precautions in set up.
> > > >
> > > > BillT
> > >
> > > Both the CG hook and the ring pair are brand new. My only guess (AKA pure speculation) is an improper (and unrecorded) repair left the whole forward fuselage weak so it is deforming under winch launch loads causing the yellow-ball to CG hook cable system to bind. FWIW, I do not suspect the hook itself.
> > >
> > > Bill D
> >
> > FWIW, CS-22 regs say a CG hook operating force can't exceed 140N (31.5 Lbs-F) I'm guessing this one takes 200 Lbs-F or more.
>
> New hook, correct hook? Correctly installed? Cracked plates? Is replacement of plates logged? Sounds like hook could be rotating under tension but you can't duplicate on ground. Cracked or broken mount plates could perhaps cause this. See these SB's
> http://www.ltb-lindner.com/g-103-ad-sb.html?file=tl_files/ltb_lindner/pdf/G%20103%20LTA%20%26%20TM%20Englisch/315-62-2%20%20CofG%20hook.pdf
> http://www.ltb-lindner.com/g-103-ad-sb.html?file=tl_files/ltb_lindner/pdf/G%20103%20LTA%20%26%20TM%20Englisch/315-62%20%20CofG%20hook.pdf

Aircraft log show compliance with both AD's on Apr 6, 2013

[Bill D]

On Sunday, May 31, 2015 at 7:58:26 PM UTC-6, Frank Whiteley wrote:
> On Sunday, May 31, 2015 at 7:02:37 PM UTC-6, Bill D wrote:
> > On Sunday, May 31, 2015 at 6:58:47 PM UTC-6, Bill D wrote:
> > > On Sunday, May 31, 2015 at 6:43:19 PM UTC-6, Bill T wrote:
> > > > I believe I remeber a Kestral that had a "stiff release" issue. He removed the seat pan and discovered that the pan was depressing with his weight in it and binding the cable. But you said you have removed the seat pans and checked all of the cables.
> > > >
> > > > My second guess would have been that there was a worn spot or nick in the "jaws" of the TOST release that might be catching on the ring under strain. But you said the TOST was fairly new. Is the TOST ring in fairly good shape and not one of the imposters that were on the market a few years back?
> > > >
> > > > It would be great if you could have a cable under load at GS=0 to visually watch the release mechanism, but that is not a safe venture without a lot of precautions in set up.
> > > >
> > > > BillT
> > >
> > > Both the CG hook and the ring pair are brand new. My only guess (AKA pure speculation) is an improper (and unrecorded) repair left the whole forward fuselage weak so it is deforming under winch launch loads causing the yellow-ball to CG hook cable system to bind. FWIW, I do not suspect the hook itself.
> > >
> > > Bill D
> >
> > FWIW, CS-22 regs say a CG hook operating force can't exceed 140N (31.5 Lbs-F) I'm guessing this one takes 200 Lbs-F or more.
>
> Has this changed since winch testing and training started, or remained consistent?
>
> Frank W

No change.

[Bill T]

Hate to launch again as an "experiment " without knowing what is really going on.
You said the instructor "rear" seat release pull took what you estimate is a 200 lb pull.
Is the front seat release having a problem?
Any problems with an auto back release at top of climb?

BillT

[Bill D]

On Sunday, May 31, 2015 at 8:12:52 PM UTC-6, Bill T wrote:
> Hate to launch again as an "experiment " without knowing what is really going on.
> You said the instructor "rear" seat release pull took what you estimate is a 200 lb pull.
> Is the front seat release having a problem?
> Any problems with an auto back release at top of climb?
>
> BillT

Yes, rear seat release.
The front seat release hasn't been tested in flight.
The "back-release" function seems to work well at the top of the launch.

[Dan Marotta]

Check for the seat pan binding the cable. Look for witness marks on the
under side of the seat pan.

Good luck!

On 5/31/2015 8:12 PM, Bill D wrote:
> On Sunday, May 31, 2015 at 7:58:26 PM UTC-6, Frank Whiteley wrote:
>> On Sunday, May 31, 2015 at 7:02:37 PM UTC-6, Bill D wrote:
>>> On Sunday, May 31, 2015 at 6:58:47 PM UTC-6, Bill D wrote:
>>>> On Sunday, May 31, 2015 at 6:43:19 PM UTC-6, Bill T wrote:
>>>>> I believe I remeber a Kestral that had a "stiff release" issue. He removed the seat pan and discovered that the pan was depressing with his weight in it and binding the cable. But you said you have removed the seat pans and checked all of the cables.
>>>>>
>>>>> My second guess would have been that there was a worn spot or nick in the "jaws" of the TOST release that might be catching on the ring under strain. But you said the TOST was fairly new. Is the TOST ring in fairly good shape and not one of the imposters that were on the market a few years back?
>>>>>
>>>>> It would be great if you could have a cable under load at GS=0 to visually watch the release mechanism, but that is not a safe venture without a lot of precautions in set up.
>>>>>
>>>>> BillT
>>>> Both the CG hook and the ring pair are brand new. My only guess (AKA pure speculation) is an improper (and unrecorded) repair left the whole forward fuselage weak so it is deforming under winch launch loads causing the yellow-ball to CG hook cable system to bind. FWIW, I do not suspect the hook itself.
>>>>
>>>> Bill D
>>> FWIW, CS-22 regs say a CG hook operating force can't exceed 140N (31.5 Lbs-F) I'm guessing this one takes 200 Lbs-F or more.
>> Has this changed since winch testing and training started, or remained consistent?
>>
>> Frank W
> No change.

--
Dan Marotta

[Bill D]

On Sunday, May 31, 2015 at 8:22:40 PM UTC-6, Dan Marotta wrote:
> Check for the seat pan binding the cable.* Look for witness marks on
> the under side of the seat pan.
>
>
>
> Good luck!
>
>
>
>
> On 5/31/2015 8:12 PM, Bill D wrote:
>
>
>
> On Sunday, May 31, 2015 at 7:58:26 PM UTC-6, Frank Whiteley wrote:
>
>
> On Sunday, May 31, 2015 at 7:02:37 PM UTC-6, Bill D wrote:
>
>
> On Sunday, May 31, 2015 at 6:58:47 PM UTC-6, Bill D wrote:
>
>
> On Sunday, May 31, 2015 at 6:43:19 PM UTC-6, Bill T wrote:
>
>
> I believe I remeber a Kestral that had a "stiff release" issue. He removed the seat pan and discovered that the pan was depressing with his weight in it and binding the cable. But you said you have removed the seat pans and checked all of the cables.
>
> My second guess would have been that there was a worn spot or nick in the "jaws" of the TOST release that might be catching on the ring under strain.. But you said the TOST was fairly new. Is the TOST ring in fairly good shape and not one of the imposters that were on the market a few years back?
>
> It would be great if you could have a cable under load at GS=0 to visually watch the release mechanism, but that is not a safe venture without a lot of precautions in set up.
>
> BillT
>
>
> Both the CG hook and the ring pair are brand new. My only guess (AKA pure speculation) is an improper (and unrecorded) repair left the whole forward fuselage weak so it is deforming under winch launch loads causing the yellow-ball to CG hook cable system to bind. FWIW, I do not suspect the hook itself.
>
> Bill D
>
>
> FWIW, CS-22 regs say a CG hook operating force can't exceed 140N (31.5 Lbs-F) I'm guessing this one takes 200 Lbs-F or more.
>
>
> Has this changed since winch testing and training started, or remained consistent?
>
> Frank W
>
>
> No change.
>
>
>
>
>
> --
>
> Dan Marotta

The cable runs are well below the bottom of the seats so it's unlikely they could rub the seat.

[Frank Whiteley]

On Sunday, May 31, 2015 at 8:05:14 PM UTC-6, Bill D wrote:
> On Sunday, May 31, 2015 at 7:46:35 PM UTC-6, Frank Whiteley wrote:
> > On Sunday, May 31, 2015 at 7:02:37 PM UTC-6, Bill D wrote:
> > > On Sunday, May 31, 2015 at 6:58:47 PM UTC-6, Bill D wrote:
> > > > On Sunday, May 31, 2015 at 6:43:19 PM UTC-6, Bill T wrote:
> > > > > I believe I remeber a Kestral that had a "stiff release" issue. He removed the seat pan and discovered that the pan was depressing with his weight in it and binding the cable. But you said you have removed the seat pans and checked all of the cables.
> > > > >
> > > > > My second guess would have been that there was a worn spot or nick in the "jaws" of the TOST release that might be catching on the ring under strain. But you said the TOST was fairly new. Is the TOST ring in fairly good shape and not one of the imposters that were on the market a few years back?
> > > > >
> > > > > It would be great if you could have a cable under load at GS=0 to visually watch the release mechanism, but that is not a safe venture without a lot of precautions in set up.
> > > > >
> > > > > BillT
> > > >
> > > > Both the CG hook and the ring pair are brand new. My only guess (AKA pure speculation) is an improper (and unrecorded) repair left the whole forward fuselage weak so it is deforming under winch launch loads causing the yellow-ball to CG hook cable system to bind. FWIW, I do not suspect the hook itself.
> > > >
> > > > Bill D
> > >
> > > FWIW, CS-22 regs say a CG hook operating force can't exceed 140N (31.5 Lbs-F) I'm guessing this one takes 200 Lbs-F or more.
> >
> > New hook, correct hook? Correctly installed? Cracked plates? Is replacement of plates logged? Sounds like hook could be rotating under tension but you can't duplicate on ground. Cracked or broken mount plates could perhaps cause this. See these SB's
> > http://www.ltb-lindner.com/g-103-ad-sb.html?file=tl_files/ltb_lindner/pdf/G%20103%20LTA%20%26%20TM%20Englisch/315-62-2%20%20CofG%20hook.pdf
> > http://www.ltb-lindner.com/g-103-ad-sb.html?file=tl_files/ltb_lindner/pdf/G%20103%20LTA%20%26%20TM%20Englisch/315-62%20%20CofG%20hook.pdf
>
> Aircraft log show compliance with both AD's on Apr 6, 2013

But hook was installed since that date? I would verify hook type and visual against the drawings in the above.

Test from front seat also.

[JJ Sinclair[_2_]]

Is it a two tow-hook system? Many G-103's removed the CG hook and replaced it with a dummy block. Was the re-installation proper? Look for an obstruction resulting in the nose hook reaching full open and not leaving CG hook sufficient movement to open. Check by removing CG cable (at hook), then actuating release system. Look for improper CG hook, improper installation, not enough cable movement at CG hook.
Hope this helps,
JJ

[Bob Kuykendall]

On Sunday, May 31, 2015 at 7:12:52 PM UTC-7, Bill T wrote:
> Hate to launch again as an "experiment " without knowing what is really going on.

I'd suggest anchoring the glider, and using a come-along to tension a rope on the hook to some modest value, say ~150 lbs, and actuate the release. That will at least give you an idea of the relationship between tow rope force and actuation force. It will also show you if anything is distorting under tow force.

[Bill D]

On Sunday, May 31, 2015 at 10:06:54 PM UTC-6, Frank Whiteley wrote:
> On Sunday, May 31, 2015 at 8:05:14 PM UTC-6, Bill D wrote:
> > On Sunday, May 31, 2015 at 7:46:35 PM UTC-6, Frank Whiteley wrote:
> > > On Sunday, May 31, 2015 at 7:02:37 PM UTC-6, Bill D wrote:
> > > > On Sunday, May 31, 2015 at 6:58:47 PM UTC-6, Bill D wrote:
> > > > > On Sunday, May 31, 2015 at 6:43:19 PM UTC-6, Bill T wrote:
> > > > > > I believe I remeber a Kestral that had a "stiff release" issue. He removed the seat pan and discovered that the pan was depressing with his weight in it and binding the cable. But you said you have removed the seat pans and checked all of the cables.
> > > > > >
> > > > > > My second guess would have been that there was a worn spot or nick in the "jaws" of the TOST release that might be catching on the ring under strain. But you said the TOST was fairly new. Is the TOST ring in fairly good shape and not one of the imposters that were on the market a few years back?
> > > > > >
> > > > > > It would be great if you could have a cable under load at GS=0 to visually watch the release mechanism, but that is not a safe venture without a lot of precautions in set up.
> > > > > >
> > > > > > BillT
> > > > >
> > > > > Both the CG hook and the ring pair are brand new. My only guess (AKA pure speculation) is an improper (and unrecorded) repair left the whole forward fuselage weak so it is deforming under winch launch loads causing the yellow-ball to CG hook cable system to bind. FWIW, I do not suspect the hook itself.
> > > > >
> > > > > Bill D
> > > >
> > > > FWIW, CS-22 regs say a CG hook operating force can't exceed 140N (31.5 Lbs-F) I'm guessing this one takes 200 Lbs-F or more.
> > >
> > > New hook, correct hook? Correctly installed? Cracked plates? Is replacement of plates logged? Sounds like hook could be rotating under tension but you can't duplicate on ground. Cracked or broken mount plates could perhaps cause this. See these SB's
> > > http://www.ltb-lindner.com/g-103-ad-sb.html?file=tl_files/ltb_lindner/pdf/G%20103%20LTA%20%26%20TM%20Englisch/315-62-2%20%20CofG%20hook.pdf
> > > http://www.ltb-lindner.com/g-103-ad-sb.html?file=tl_files/ltb_lindner/pdf/G%20103%20LTA%20%26%20TM%20Englisch/315-62%20%20CofG%20hook.pdf
> >
> > Aircraft log show compliance with both AD's on Apr 6, 2013
>
> But hook was installed since that date? I would verify hook type and visual against the drawings in the above.
>
> Test from front seat also.

I was told it was but it's sure worth checking.

[Bill D]

On Monday, June 1, 2015 at 7:26:07 AM UTC-6, JJ Sinclair wrote:
> Is it a two tow-hook system?

Yes



Many G-103's removed the CG hook and replaced it with a dummy block. Was the re-installation proper?

I can't determine that from the maintenance log but it's worth checking.



Look for an obstruction resulting in the nose hook reaching full open and not leaving CG hook sufficient movement to open.

That was my first thought too but I've been lectured that the Twin Astir works differently.

Check by removing CG cable (at hook), then actuating release system. Look for improper CG hook, improper installation, not enough cable movement at CG hook.


> Hope this helps,

It helps a lot JJ

[Bill D]

On Monday, June 1, 2015 at 8:25:42 AM UTC-6, Bob Kuykendall wrote:
> On Sunday, May 31, 2015 at 7:12:52 PM UTC-7, Bill T wrote:
> > Hate to launch again as an "experiment " without knowing what is really going on.
>
> I'd suggest anchoring the glider, and using a come-along to tension a rope on the hook to some modest value, say ~150 lbs, and actuate the release. That will at least give you an idea of the relationship between tow rope force and actuation force. It will also show you if anything is distorting under tow force.

We're thinking along those lines too. However, to check a CG hook at the rope angles normally experienced, the pull angle has to be something line 45 degrees down from horizontal. That's going to be complicated.

[[email protected]]

On Monday, June 1, 2015 at 3:33:14 PM UTC+1, Bill D wrote:
> On Monday, June 1, 2015 at 8:25:42 AM UTC-6, Bob Kuykendall wrote:
> > On Sunday, May 31, 2015 at 7:12:52 PM UTC-7, Bill T wrote:
> > > Hate to launch again as an "experiment " without knowing what is really going on.
> >
> > I'd suggest anchoring the glider, and using a come-along to tension a rope on the hook to some modest value, say ~150 lbs, and actuate the release.. That will at least give you an idea of the relationship between tow rope force and actuation force. It will also show you if anything is distorting under tow force.
>
> We're thinking along those lines too. However, to check a CG hook at the rope angles normally experienced, the pull angle has to be something line 45 degrees down from horizontal. That's going to be complicated.

Lay the fuselage on its side??

[Dan Marotta]

Perhaps a pulley mounted to a 2 x 12 of sufficient length that the
glider sits on the board to hold it down. Position the glider on the
board to get the desired angle and put a couple of people in the
cockpit. Use a spring scale and come along to set the desired tension.

<snip>

> We're thinking along those lines too. However, to check a CG hook at the rope angles normally experienced, the pull angle has to be something line 45 degrees down from horizontal. That's going to be complicated.

--
Dan Marotta

[Papa3[_2_]]

On Monday, June 1, 2015 at 11:26:28 AM UTC-4, Dan Marotta wrote:
> Perhaps a pulley mounted to a 2 x 12 of sufficient length that the
> glider sits on the board to hold it down.** Position the glider on
> the board to get the desired angle and put a couple of people in the
> cockpit.* Use a spring scale and come along to set the desired
> tension.
>
>
>
> <snip>
>
>
> We're thinking along those lines too. However, to check a CG hook at the rope angles normally experienced, the pull angle has to be something line 45 degrees down from horizontal. That's going to be complicated.
>
>
>
>
>
> --
>
> Dan Marotta

Yup. Was involved in a similar exercise many years ago when John Campbell was investigating critical angles on Schweitzer releases. If the glider is assembled, you can get a group of folks together and lift it onto some tall saw horses supporting the wings near the root. Use big pads to avoid crushing the skin. Even better would be to take the wings off and support using the lift pin hardpoints. If you do this over a solid tie down (airport tiedown ring), you'll only need a small pulley and you can move the fuselage forward or backwards to get the required angles.

[Craig Funston]

On Monday, June 1, 2015 at 8:45:14 AM UTC-7, Papa3 wrote:
> On Monday, June 1, 2015 at 11:26:28 AM UTC-4, Dan Marotta wrote:
> > Perhaps a pulley mounted to a 2 x 12 of sufficient length that the
> > glider sits on the board to hold it down.** Position the glider on
> > the board to get the desired angle and put a couple of people in the
> > cockpit.* Use a spring scale and come along to set the desired
> > tension.
> >
> >
> >
> > <snip>
> >
> >
> > We're thinking along those lines too. However, to check a CG hook at the rope angles normally experienced, the pull angle has to be something line 45 degrees down from horizontal. That's going to be complicated.
> >
> >
> >
> >
> >
> > --
> >
> > Dan Marotta
>
> Yup. Was involved in a similar exercise many years ago when John Campbell was investigating critical angles on Schweitzer releases. If the glider is assembled, you can get a group of folks together and lift it onto some tall saw horses supporting the wings near the root. Use big pads to avoid crushing the skin. Even better would be to take the wings off and support using the lift pin hardpoints. If you do this over a solid tie down (airport tiedown ring), you'll only need a small pulley and you can move the fuselage forward or backwards to get the required angles.

A variation of Dan's idea is pretty simple. Take a 12 ft. or so plank with one end under the main wheel and an eyebolt at the desired point under the CG hook. Let the free end of the plank extend beyond the nose of the glider and link the hook to the eyebolt so that the plank is held up at the nose end. That allows someone to sit on the tail and another person to put tension on the rope by pushing down on free end of the plank.

[Bill D]

On Sunday, May 31, 2015 at 7:58:26 PM UTC-6, Frank Whiteley wrote:
> On Sunday, May 31, 2015 at 7:02:37 PM UTC-6, Bill D wrote:
> > On Sunday, May 31, 2015 at 6:58:47 PM UTC-6, Bill D wrote:
> > > On Sunday, May 31, 2015 at 6:43:19 PM UTC-6, Bill T wrote:
> > > > I believe I remeber a Kestral that had a "stiff release" issue. He removed the seat pan and discovered that the pan was depressing with his weight in it and binding the cable. But you said you have removed the seat pans and checked all of the cables.
> > > >
> > > > My second guess would have been that there was a worn spot or nick in the "jaws" of the TOST release that might be catching on the ring under strain. But you said the TOST was fairly new. Is the TOST ring in fairly good shape and not one of the imposters that were on the market a few years back?
> > > >
> > > > It would be great if you could have a cable under load at GS=0 to visually watch the release mechanism, but that is not a safe venture without a lot of precautions in set up.
> > > >
> > > > BillT
> > >
> > > Both the CG hook and the ring pair are brand new. My only guess (AKA pure speculation) is an improper (and unrecorded) repair left the whole forward fuselage weak so it is deforming under winch launch loads causing the yellow-ball to CG hook cable system to bind. FWIW, I do not suspect the hook itself.
> > >
> > > Bill D
> >
> > FWIW, CS-22 regs say a CG hook operating force can't exceed 140N (31.5 Lbs-F) I'm guessing this one takes 200 Lbs-F or more.
>
> Has this changed since winch testing and training started, or remained consistent?
>
> Frank W

Update,

I finally got knowledgable help to do a better ramp test. Pulling on a strop by hand at a typical winch angle, I can feel a noticible step in the release process as the yellow knob is very slowly pulled. It seems like there is some irregularity in the "beak" part of the hook which may be large enough to cause the hard release problem. Since this glider has never seen winch launch before, it could be the CG hook was used for tie-down or an old hook was used as a "box check" to get through an annual. More investigation results to follow.

[Eric Munk]

- Mountings bolts/nuts overtightened during installation(some earlier Tost
releases do not have the mounting bolt bushings inside the hook)?
- Nose-release blocked (had this on an ASK-21 with a sheared off
M6-bolthead fallen inside the release, very hard to find)?
- Actuator-arms of new release not in the same position as before removal
of old release (they are adjustable) causing pre-tension on actuation
cable?
- Dirt/debris in any actuating cable jackets (e.g. Bowden)?
- Wrong hardness mountings bolts (4.6) fitted, distorting bolts?

If release just installed, mounting bolt tightening or actuator arm
position usually to blame.